A fourth generation (4G) wireless network is an all Internet protocol (IP) wireless network in which different advanced multimedia application services (e.g., voice over IP (VoIP) content, video content, etc.) are delivered over IP. 4G wireless networks include a radio access network, such as, for example, a long term evolution (LTE) network or an enhanced high rate packet data (eHRPD) network. 4G wireless networks also include an IP multimedia subsystem (IMS) network and a wireless core network, referred to as an evolved packet core (EPC) network. The LTE network is often called an evolved universal terrestrial radio access network (E-UTRAN). The EPC network is an all-IP packet-switched core network that supports high-speed wireless and wireline broadband access technologies. An evolved packet system (EPS) is defined to include the LTE (or eHRPD) network and the EPC network.
Two components of the EPS are a home subscriber server (HSS) and a mobility management entity (MME). The HSS is provided in the IMS network and includes a database, which stores user equipment (UE) subscriber profile information. The MME is provided in the EPC network and is responsible for handling control plane signaling with UEs as the UEs are provided access to different packet data networks (PDNs).
Non-access stratum (NAS) is a highest stratum of a control plane between a UE and a MME. NAS protocols support mobility of the UE and further support session management procedures to establish and maintain IP connectivity between the UE and a packet data network (PDN) gateway (PGW). NAS protocols define rules for a mapping between parameters during inter-system mobility with third generation (3G) networks. NAS protocols also provide NAS security by integrity protection and ciphering of NAS signaling messages. To enable transfer of application protocol messages between the MME and the UE, NAS protocols define a generic container message on the downlink (e.g., a downlink generic NAS transport message) and define another generic container message on the uplink (e.g., an uplink generic NAS transport message). However, current networks do not fully utilize the capabilities of NAS messaging and are unable to exchange enough information via a typical IP transport.